Communication system, base station apparatus, data transmission method and non-transitory computer readable medium storing program

ABSTRACT

A communication system, (a base station apparatus, a data transmission method, and a program) in which unnecessary signalings do not occur in a large quantity as a result of the execution of a SON function, includes an eNB and an eNB that performs data transmission/reception with the eNB, in which the eNB includes a signal transmission/reception unit that transmits information to the eNB, the information being used to determine whether or not autonomous setting information should be transmitted from the eNB to the eNB.

TECHNICAL FIELD

The present invention relates to a communication system including a basestation apparatus that autonomously performs apparatus setting.

BACKGROUND ART

When setting is performed on a base station included in a mobilecommunication network, an SON (Self Organizing Networks) function forcollecting and analyzing quality measurement data and the like from aterminal(s) and a base station(s) and autonomously performing theapparatus setting is used. By using the SON function, it is possible toimprove the quality of the network and reduce the operation cost.

For example, an operation performed by an HNB (Home NodeB) or an HeNB(Home eNodeB), which is a home-use compact base station, in which theHNB (Home NodeB) or the HeNB (Home eNodeB) itself automatically performsPlug-and-Play, receives a radio wave (network listening), and determinesa radio parameter(s) such as a frequency (EARFCN: E-UTRA Absolute RadioFrequency Channel Number) and a PCI (Physical Cell ID) is considered tobe one of the SON operations. Further, an operation in which the statusof a radio wave (such as a distribution of pilot channels, a neighboringcell(s), interference, a throughput status, a handover failure rate, aradio load status, and PM (Performance Management)) is measured over along period, and an OAM parameter(s) is thereby optimized by astatistical technique is also considered to be one of the SONoperations.

A configuration of a mobile communication system compliant with an LTEradio communication scheme is explained with reference to FIG. 16. AneNB 10, an eNB 11, and an eNB 12 are base stations compliant with theLTE radio communication scheme. An interface between eNBs is called“X2-interface” (see Non-patent literature 1: 3G3GPP TS36.300). An EM 14is an Element Manager that controls the eNBs, and an NM 15 is ahigher-level apparatus of the EM 14 on the OAM, and represents a NetworkManager that maintains and monitors the entire network. An MME/S-GW 13represents a core network, and performs movement management control andsession management control. The interface between an eNB and theMME/S-GW is defined as “S1-interface”.

Next, an OAM reference model disclosed in Non-patent literature 2 (3GPPTS32.101) is explained with reference to FIG. 17. In this figure,respective definitions for an NM (Network Manager), an EM (ElementManager), and an NE (Network Element) are based on 3GPP TS32.101.

NEs 21 to 25 are Network Elements. For example, an eNB (E-UTRAN NodeB),an HeNB, a NodeB, an RNC, and an HNB (Home NodeB) correspond to theseelements. DMs 31 to 33 are Domain Managers, and hold a Network Elementmanagement function and a sub-network domain management function. EMs 34to 37 are Element Managers, and provide a Network Element managementfunction. NMs 41 and 42 are Network Managers and are located on a higherlevel of the EMs. The NMs 41 and 42 manages a network supported by theEMs. When an EM function is accommodated in an NE, the NE is directlyaccessed by the NM. The NMs 41 and 42 are connected to EnterpriseSystems 50 formed by a server apparatus and so on.

Among others, the interface between an EM and an NM or between an NEhaving an EM function and an NM is defined as a “Type-2 interface”. Itis also defined as an “ITF-N (North bound interface)”, which is an openinterface defined in the 3GPP standardization specifications series.

Next, an SON solution implemented in the above-described OAM referencemodel will be explained. In the SON solution, there are three methods,i.e., a Centralised SON, a Distributed SON, and a Hybrid SON asmentioned in Non-patent literature 3 (3GPP TS32.500 Ver10.1.0). TheCentralised SON is an SON solution in which an SON algorithm isimplemented in an OAM system. There are two types of the CentralisedSON, i.e., an NM-Centralised SON in which an SON algorithm isimplemented in a Network Management level and an EM-Centralised SON inwhich an SON algorithm is implemented in an Element Management level.The Distributed SON is an SON solution in which an SON algorithm isimplemented in a Network Element level. Further, the Hybrid SON is anSON solution in which an SON algorithm is implemented in a plurality oflevels including an NE, or an EM and an NM.

These SON solutions are appropriately selected according to the detailsof the automatic setting, the OAM target apparatus to be automaticallyoptimized, the SON algorithm, or the required performance. Further, theSON solution is implemented in a vendor apparatus, i.e., a communicationapparatus.

In the case of the Distributed SON, since the SON algorithm isimplemented in an NE, the OAM parameters can be immediately changed.Therefore, the Distributed SON is suitable to optimize the OAMparameters in real-time. However, in order for the NE itself to optimizethe OAM parameters, the NE needs to frequently collect information fromneighboring NEs by using protocol messages. Therefore, when theDistributed SON is performed, the number of signalings between NEsincreases. Further, there is a restriction that the range the NE canrecognize is limited to cells adjacent to the NE or to the range ofcells which such adjacent cells are adjacent to.

In contrast, in the Centralised SON, a plurality of NEs in a wide rangecan be collectively managed in a centralized manner and theirstatistical information can be used. Therefore, the Centralised SON issuitable to optimize the entire network at long intervals. Further,there is a merit that there is no need to use signaling such as anX2AP-message between NEs.

In a network, there is a possibility that a plurality of vendorapparatuses (such as NEs, EMs, and NMs) are used and a different SONsolution is used for each apparatus by using an algorithm (SONalgorithm) or an SON performing method unique to the vendor.

For example, as mentioned in Non-patent literature 4 (TR36.902), as aPCI assignment optimization method, it is necessary to assign PCIs sothat PCI Collision-free and PCI Confusion-free are guaranteed. However,whether the PCI assignment method should be implemented by theDistributed SON, the Centralised SON, or the Hybrid SON is dependent onthe implementation of the apparatus vendor. That is, when the PCIassignment optimization algorithm is implemented on the NE side, it isimplemented by the Distributed SON. Further, when the PCI assignmentoptimization algorithm is implemented in the EM or the NM, it isimplemented by the Centralised SON. Further, when the PCI assignmentoptimization algorithm is implemented in both the NE and the EM/NM, itis implemented by the Hybrid SON. As described above, how it isimplemented is dependent on the vendor implementation.

As typical use cases of the SON (SON functions), PCI assignmentoptimization, ANR (Automatic Neighbour Relation), MRO (MobilityRobustness Optimisation), MLB (Mobility Load Balancing), RACHOptimisation, Self Healing, ICIC (Inter-cell Interference Coordination),CoC (Cell outage Compensation) and so on are defined in 3GPPspecifications (3GPP TS36.300 Ver10.0.0, TR36.902 V9.3.1, TS32.500Ver10.0.0, Non-patent literature 5: TS32.541 Ver10.0.0 and so on).

Further, as defined in TR36.902, the PCI Collision-free is to guaranteethat PCIs are unique in an area covered by a cell. Further, the PCIconfusion-free is to guarantee that PCIs are unique in neighboringcells.

CITATION LIST Non Patent Literature

-   Non-Patent literature 1: 3GPP TS 36.300 V10.5.0 “E-UTRA and E-UTRAN    Overall description Stage 2” September 2011-   Non-Patent literature 2: 3GPP TS 32.101 V10.0.0 “Telecommunication    management; Principles and high level requirements (Release 10)”    September 2010-   Non-Patent literature 3: 3GPP TS 32.500 V10.1.0 “Telecommunication    management; Self-Organizing Networks (SON); Concepts and    requirements (Release 10)” September 2010-   Non-Patent literature 4: 3GPP TR 36.902 V9.3.1 “E-UTRAN;    Self-configuring and self-optimizing network (SON) use cases and    solutions (Release 9)” March 2011-   Non-Patent literature 5: 3GPP TS 32.541 V10.0.0 “Telecommunication    management; Self-Organizing Networks (SON); Self-healing concepts    and requirements (Release 10)” March 2011-   Non-Patent literature 6: 3GPP TS 36.423 V10.3.0 “E-UTRAN X2    application protocol (X2AP) (Release 10)” September 2011

SUMMARY OF INVENTION Technical Problem

When the Distributed SON and the Centralised SON are allowed to be usedamong multiple vendors in a mixed manner, the below-explained problemsoccur. The problems are explained based on an LTE system, withparticular emphasis on an SON system using an eNodeB(s).

A first problem is explained hereinafter. In an X2-interface, variousprotocols are defined for the purpose of the SON. However, informationon how a neighboring eNodeB(s) is implementing an SON is not sent byusing an X2AP-message. Therefore, the eNodeB has to send informationabout the SON function by using an X2AP-message at all timesirrespective of whether the Centralised SON is implemented or theDistributed SON is implemented in the neighboring eNodeB(s). As aresult, there is a problem that even when the neighboring eNodeB(s)adopts the Centralised SON, the X2AP-messages cannot be reduced.

For example, in an X2AP (Non-patent literature 6: 3GPP TS36.423)procedure, eNBs can send neighboring “Neighbour relation” information toeach other by using:

-   X2 SETUP; and-   ENB CONFIGURATION UPDATE.

For example, in the X2 SETUP procedure, an eNB can send not only cellinformation (Served Cell Information) managed by the eNB itself but alsoneighboring cell information (Neighbour Information) when an X2 isestablished. Further, in the X2AP ENB CONFIGURATION UPDATE procedure, aneNB can send not only the newest cell information (added cellinformation, deleted cell information, and corrected cell information)managed by the eNB itself but also neighboring cell information. Theneighboring cell information includes an ECGI (E-UTRAN Cell GlobalIdentifier), a PCI (Physical Cell Identifier), an EARFCN and so on. Forexample, an eNB can recognize not only the PCI (Physical CellIdentifier) of a neighboring cell(s) but also the PCI information of aneNB(s) of a cell(s) adjacent to the neighboring cell(s).

The PCI information is an important parameter when an UE identifies acell. In the LTE, the maximum number of PCIs that can be assigned is504. Therefore, in the system, PCIs need to be repeatedly used. The PCIis an ID that is necessary to generate signaling necessary for a Cellsearch operation of an UE and for synchronous detection, and is one ofthe most important IDs among the IDs used in eNBs. In a radio system, ifan optimal value is not used for the PCI, a handover failure caused byincorrect handover routing to a Target eNB due to the occurrence of PCIconfusion could occur. Further, because of the increase of interferencedue to the occurrence of PCI collision, a decrease of throughput,synchronization loss, and so on could occur due to the deterioration ofchannel estimation performance in UEs. As a result, the quality ofservice to be provided to end users could deteriorate. As describedabove, to avoid the PCI Collision and the PCI Confusion, as mentioned in3GPP TS36.300, the PCI information of a neighboring cell(s), which issent by the X2 SETUP procedure, is important in order to implement thePCI Optimisation.

In contrast, in the existing 3GPP TS36.423, an eNB does not sendinformation on what kind of SON solution each cell is performing.Further, in TS32.762 Ver10.3.0 (E-UTRAN Network Resource Model (NRM)),in an ExternalEUtranGenericCell, an ExternalENBFunction, and anEUtranRelation, information on what kind of SON solution a neighboringcell(s) is using to implement an SON use case (SON function) is notsent. Therefore, when the neighboring eNB receives an X2AP-message, theneighboring eNB has to transmit an X2AP-message to other eNBs at alltimes. As a result, the below-explained problem occurs in the PCIOptimisation.

An example of a PCI change operation in a case where a Distributed SONis used is explained hereinafter with reference to FIG. 18. Assume thatan eNB 100 is performing a Distributed SON in a PCI assignment method.Assume also that the PCI value of a cell that is under the management ofthe eNB 100 is 3. As PCI Collision or PCI Confusion is detected, the PCIoptimization function of the Distributed SON operates. When the PCIvalue is changed, for example, from 3 to 200, the eNB notifiesneighboring eNBs 101, 102, 103, 104, 105 and 106 about the changed PCIvalue by transmitting an X2AP: X2 SETUP message or an X2 ENBCONFIGURATION UPDATE message to the neighboring eNBs. That is, in a casewhere the number of eNBs that manage cells adjacent to the cell of agiven eNB is six as shown in FIG. 18, when the PCI of the cell managedby the eNB 100 is changed, the eNB sends an X2AP-message six times intotal. Note that in this example, each eNB manages only one cell for thepurpose of simplifying the explanation.

Further, to avoid the problem of PCI collision and PCI Confusion withcells adjacent to the neighboring cells, it is also necessary to sendinformation on a change(s) relating to the neighboring cell informationby the X2AP-procedure. Therefore, the eNBs 101, 102, 103, 104, 105 and106 adjacent to the eNB 100 notify the neighboring eNBs that the PCIvalue of the cell under the management of the eNB 100 is changed from 3to 200 by using an X2AP: X2 SETUP message or an X2 ENB CONFIGURATIONUPDATE message.

FIG. 19 shows that the eNB 101 transmits an X2AP-message to eNBs 107,108, 109, 106, 100 and 102, i.e., transmits an X2AP-message six times intotal. Similarly, eNBs 102, 103, 104, 105 and 106 transmit an X2AP: X2SETUP message or an X2 ENB CONFIGURATION UPDATE message to theirneighboring eNBs.

The above-explained operation is an example of an operation for theDistributed SON according to the 3GPP standardization specificationsTS36.423. As described above, in a case where the number of neighboringcells is six and the number of neighboring X2-links is also six, thenumber of X2AP-messages transmitted to send information about the changeof one cell is 36 (6×6=36) messages.

In an actual operation, when macro-cells are adjacent to each other, thetypical number of X2-links is 32. Therefore, the number of transmissionsof X2AP-messages is 1024 (32×32=1024). That is, when a certain one ofthe PCIs is changed, X2AP-signalings occur 1024 times. Similarly,assuming a network in which in addition to macro-cells under themanagement of macro-base station, macro-cells having a small cellradius, pico-cells, and femto-cells exist in a mixed manner, the numberof neighboring X2-links increases. For example, assuming the number ofneighboring X2-links is 128, X2AP-signalings occur 16384 (128×128=16384)times. That is, when the PCI of only one cell is changed in an eNB,notifications of X2AP-signalings need to be performed “N_x2×N_x2=(squareof N_x2)” times, where N_x2 is the number of X2-links. Because of theincrease of the number of signaling messages as described above, thereis a problem that congestion occurs in each node. Further, in a casewhere a PCI is sent as a result of the notification of an X2AP-messageand PCI Confusion occurs in a neighboring neighboring eNB, when a PCI isfurther changed in the neighboring neighboring eNB, a PCI is furthersent.

Although an example case where a PCI is changed is explained for thisproblem, similar problems also occur for the ECGI and the EARFCN, whichare neighboring cell information.

As described above, since the Distributed SON having an SON functionexists on the NE side, NEs notify each other about necessary changeinformation through the X2-interface in a meshed pattern. As a result,there is a problem that the quantity of signals for X2AP-messagesgreatly increases. There is a possibility that: such a great increase inthe quantity of the signals may cause a shortage of signal transmissionbuffers or signal reception buffers, make an eNB(s) unable to continuethe normal operation, and cause an unstable state. Further, similarly,there is a possibility that as the number of signals increases, theprocessing performance may increase, thus making eNB(s) unable tocontinue the normal operation and causing an unstable state.

In contrast, in the case of the Centralised SON, the EM or the NMcontrols subordinate eNBs. Therefore, even when the PCI of a given eNBis changed, there is no need to send information about the PCI change,provided that the given eNB is also under the management of the same EMor the same NM, because the EM or the NM also manages the PCI change ofthat eNB. Therefore, the problem of the quantity of the signals greatlyincreasing due to the increase of X2AP-messages, which occurs in theDistributed SON, does not occur. However, in an actual operation,depending on the SON function algorithm implementation method of theapparatus (NE) vendor, there is a possibility that a Distributed SON anda Centralised SON exist in a mixed manner. For example, a DistributedSON and a Centralised SON existing in a mixed manner is explained withreference to FIG. 20.

Assume that eNBs 100, 102, 104, 108, 110 and 112 are controlled by an EM200 and that the EM 200 has an SON function. Assume that a DistributedSON is performed for the other eNBs, i.e., the eNBs 101, 103, 105, 106,107 and 109.

In the existing X2AP-messages, information about in which node aneighboring eNB(s) is implementing an SON function is not sent. Further,information about what kind of SON solution is used to implement an SONfunction is also not sent. For example, the eNB 106 that is implementinga Distributed SON does not recognize whether the eNB 100 is implementinga Distributed SON or implementing a Centralised SON. The eNB 106 is alsonot notified about the EM, the NM, or the like that is performing theSON function of the eNB 100.

When the PCI value of a cell under the management of the eNB 100 ischanged from 3 to 200, the eNB 100 does not transmit an X2AP-message tothe neighboring eNBs 104 and 102 because the eNBs 104 and 102 arecontrolled by the same EM 200 and they are implementing a CentralisedSON. In contrast, the eNB 100 sends an X2AP-message to the eNBs 106,101, 103 and 105 for the PCI change.

The eNBs 101, 103, 105 and 106, which have received the PCI changenotification, do not recognize which SON function the neighboring eNBsare implementing and what kind of SON solution is used to implement theSON function. Therefore, as shown in FIG. 20, the eNB 101 notifies theeNBs 102, 106, 107, 108 and 109 about the PCI value change of the eNB100, and the eNB 105 notifies the eNB 112 about the PCI value change ofthe eNB 100. Further, the eNB 106 notifies the eNB 110 about the PCIvalue change of the eNB 100.

In actuality, since the eNBs 108, 110 and 112 are controlled by the SONfunction of the same EM 200 as for the eNB 100, the notifications areunnecessary. That is, when the eNBs 108, 110 and 112 receive anotification about a PCI change through an X2A-message, they send it tothe SON function disposed in the EM 200. However, the EM 200 has alreadyrecognized the PCI change itself of the eNB 100. Therefore, the signalssent to the eNBs 108, 110 and 112 are unnecessary signals.

As described above, when a Distributed SON and a Centralised SON existin a mixed manner, signalings that are unnecessary for the nodesperforming the Centralised SON occur because neighboring eNBs do notsend the information about what kind of SON solution is implemented inwhich node to each other. Therefore, the advantage of the CentralisedSON is significantly lost. In the above-shown example, the number ofneighboring links is six at the maximum. However, assuming the number ofX2-links is 128 for the neighboring eNBs, there is a possibility thatunnecessary X2AP-signalings occur 128 times for one eNB. There is apossibility that the occurrences of such signalings in a large quantitycause a shortage of communication buffers and increase the number ofsignal processing processes, thus making the operation of the eNB(s) orthe EM (or the NM) unstable and causing failures in the apparatuses. Asdescribed above, as the existing problem, there is a problem that sinceinformation about which node is implementing an SON function is not sentamong neighboring eNBs in the X2P-procedure, an eNB(s) has to send a PCIchange notification and the like by using an X2AP-message at all times.

A second problem is explained hereinafter. For example, althoughX2AP-messages such as an MRO (Mobility Robustness Optimisation) and anMLB (Mobility Load Balancing) are defined in 3GPP TS36.423 as shown inFIG. 21, it does not necessarily mean that all of neighboring eNBssupport the same SON function(s). For example, a certain eNB can improvethe handover success rate by optimizing the threshold and/or theparameter of the handover by using MRO (Mobility RobustnessOptimisation). It should be noted that in the X2AP-procedure, it ispossible to request the opposed eNB to change the handover thresholdand/or a CIO (Cell individual offset) by using a Mobility Setting Changeprocedure.

Similarly, in the MLB (Mobility Load Balancing) procedure, the handoverparameter and/or the CIO are changed based on load information (HW(hardware) load, TNL (transport network layer) load, and PRB (Physicalresource block)) among eNBs so that the load is controlled among theeNBs. To make a change like this, in the X2AP-procedure, a notificationis provided to the opposed eNB through the Mobility Setting Changeprocedure. Further, when Too Late Handover, Too Early Handover, and HOto Wrong Cell (TS36.300) are to be detected, a procedure such as a RadioLink Failure Indication and a Handover Event Report, which areX2AP-procedures, is used to recognize these phenomena. FIG. 21 shows anexample of a correspondence relation between X2AP-procedures and SON usecases (SON functions).

However, when a plurality of vendor apparatuses exist in a mixed manner,all of neighboring eNBs do not necessarily support the same SONfunction(s). Therefore, there is a possibility that an eNB that supportsthe MRO starts a Radio Link Failure Indication, a Handover Event Report,or a Mobility State Change procedure for an eNB that does not supportthe MRO. Similarly, there is a possibility that it starts up a ResourceStatus Reporting Initiation or a Mobility Settings Change procedure foran eNB that does not support the MLB. Therefore, unnecessaryX2AP-signalings occur in a large quantity, thus causing problems of thecommunication buffer shortage of an eNB(s) and an increase in the numberof signal processing processes.

The present invention has been made to solve at least one of theabove-described problems, and an object thereof is to provide acommunication system, a base station apparatus, a data transmissionmethod, and a program in which unnecessary signalings do not occur inlarge quantity as a result of the execution of a SON function.

Solution to Problem

A communication system according to a first aspect of the presentinvention includes: a first communication apparatus; and a secondcommunication apparatus that performs data transmission/reception withthe first communication apparatus, in which the first communicationapparatus includes a transmission unit that transmits information to thesecond communication apparatus, the information being used to determinewhether or not autonomous setting information should be transmitted fromthe second communication apparatus to the first communication apparatus.

A base station apparatus according to a second aspect of the presentinvention is a base station apparatus adjacent to a first base stationapparatus, including a transmission unit that transmits information tothe first communication apparatus, the information being used in thefirst base station apparatus to determine whether or not autonomoussetting information should be transmitted to the base station apparatus.

A data transmission method according to a third aspect of the presentinvention is a data transmission method performed in a base stationapparatus adjacent to a first base station apparatus, includingtransmitting information to the first communication apparatus, theinformation being used in the first base station apparatus to determinewhether or not autonomous setting information should be transmitted tothe base station apparatus.

A program according to a fourth aspect of the present invention is aprogram that causes a computer in a base station apparatus adjacent to afirst base station apparatus to execute a step of transmittinginformation to the first communication apparatus, the information beingused in the first base station apparatus to determine whether or notautonomous setting information should be transmitted to the base stationapparatus.

Advantageous Effects of Invention

According to the present invention, it is possible to provide acommunication system, a base station apparatus, a data transmissionmethod, and a program in which unnecessary signalings do not occur inlarge quantity as a result of the execution of a SON function.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a configuration diagram of a base station apparatus accordingto a first exemplary embodiment;

FIG. 2 is a table showing information elements of an X2 SETUP REQUESTmessage according to the first exemplary embodiment;

FIG. 3 is a table showing information elements of an X2 SETUP RESPONSEmessage according to the first exemplary embodiment;

FIG. 4A is a table showing details of setting of SON SolutionInformation according to the first exemplary embodiment;

FIG. 4B is a table showing details of setting of SON SolutionInformation according to the first exemplary embodiment;

FIG. 5 is a table showing details of setting of Served Cell Informationaccording to the first exemplary embodiment;

FIG. 6 is a table showing information elements of an ENB CONFIGURATIONUPDATE message according to the first exemplary embodiment;

FIG. 7 is a sequence diagram showing a process for sending informationabout an SON function implementation method according to the firstexemplary embodiment;

FIG. 8 is a sequence diagram showing a process for sending informationabout an SON function implementation method according to the firstexemplary embodiment;

FIG. 9 is a table showing a configuration of a database unit accordingto the first exemplary embodiment;

FIG. 10 is a flowchart showing an X2AP-message transmitting process inan eNB according to the first exemplary embodiment;

FIG. 11 is a table showing information about an SON function of an eNBto be sent from an NM to an EM through a Type-2 interface according to asecond exemplary embodiment;

FIG. 12 is a configuration diagram of a communication system accordingto the second exemplary embodiment;

FIG. 13 is a sequence diagram showing an X2AP establishing processaccording to a third exemplary embodiment;

FIG. 14 is a sequence diagram showing an X2AP establishing processaccording to the third exemplary embodiment;

FIG. 15 is a table showing information elements of an X2 SETUP RESPONSEmessage according to the third exemplary embodiment;

FIG. 16 is a configuration diagram of a mobile communication systemcompliant with an LTE radio communication scheme;

FIG. 17 is a diagram showing an OAM reference model;

FIG. 18 is a diagram sowing a PCI change operation;

FIG. 19 is a diagram sowing a PCI change operation;

FIG. 20 is a diagram sowing a PCI change operation; and

FIG. 21 is a table showing an X2AP-message related to an SON function.

DESCRIPTION OF EMBODIMENTS First Exemplary Embodiment

Exemplary embodiments according to the present invention are explainedhereinafter with reference to the drawings. A configuration example of abase station apparatus according to a first exemplary embodiment of thepresent invention is explained with reference to FIG. 1. Specifically, aconfiguration example of an eNB used as a base station in a 3GPP LTEradio communication scheme is explained. An eNB 100 includes a controlunit 1101, a signal transmission/reception unit 1102, and a databaseunit 1103.

The signal transmission/reception unit 1102 performs thetransmission/reception of signals with other eNBs, an MME, an EM and soon. Examples of the signals to be transmitted/received include an S1AP,an X2AP, a CORBA, an SOAP, an SNMP and so on. The S1AP is a signal thatis transmitted/received between an eNB 100 and an MME. The X2AP is asignal that is transmitted/received between eNBs.

The signal transmission/reception unit 1102 transmits information aboutwhether or not autonomous setting information should be transmitted fromother eNBs to the eNB 100, to the other eNBs by using the X2AP. Theautonomous setting information includes, for example, a PCI value,information that is transmitted at the time of execution of an MRO or anMLB, and so on. When a PCI value or the like is changed in a neighboringeNB and the eNB 100 is notified about the changed PCI value, the eNB 100autonomously sets the PCI value of the neighboring eNB in the eNB 100itself. Further, when the eNB 100 needs to change the PCI value of theeNB 100 itself as a result of the PCI value change setting in theneighboring eNB, for example, when PCI Confusion or the like couldoccur, the eNB 100 autonomously changes the PCI value of the eNB 100itself. In the case where an SON function supported by the eNB itself ora Centralised SON is used, the information about whether or notautonomous setting information should be transmitted includes the EMthat manages the eNB itself, the node identification information of theNM, or the like. The SON function is, for example, a function(s)mentioned in the SON use cases shown in FIG. 21.

Examples of the information that is transmitted from the signaltransmission/reception unit 1102 of the eNB 100 to other eNBs include anX2 SETUP REQUEST message, an X2 SETUP RESPONSE message, an ENBCONFIGURATION UPDATE message, SON Solution Information, Served CellInformation and so on. Note that the X2 SETUP RESPONSE message is aresponse signal to the X2 SETUP REQUEST message.

Next, information elements that are set in the X2 SETUP REQUEST messageand the X2 SETUP RESPONSE message are explained with reference to FIGS.2 and 3. FIG. 2 shows an X2 SETUP REQUEST message. FIG. 3 shows an X2SETUP RESPONSE message. As shown in FIGS. 2 and 3, an informationelement “SON Solution Information” is defined in the X2 SETUP REQUESTmessage and the X2 SETUP RESPONSE message.

FIGS. 4A and 4B show specific elements set in the SON SolutionInformation. In the SON Solution Information, functions to be executedin the SON (SON functions) are specified. For example, a PCI Assignment,an ANR (Automatic Neighbor Relation), an MRO (Mobility RobustnessOptimization), an MLB (Mobility Load Balancing), a CCO (Coverage andCapacity Optimization), an Energy Serving, an ICIC (Inter-CellInterference Coordination) and CoC are shown as SON functions. Further,in the SON Solution Information, information about which SON solution isused among a Centralised SON, a Hybrid SON, and a Distributed SON toimplement each SON function is also shown. For example, in the SONSolution Information, when a Centralised SON or a Hybrid SON is to beused, “Centralised”, “Hybrid” or the like is explicitly set. As for theSON functions for which “Centralised”, “Hybrid” or the like is notexplicitly set, they may be implemented by using a Distributed SON.

Further, for the SON functions that are to be executed by using aCentralised SON or a Hybrid SON, the node identification information ofa higher-level apparatus that executes the SON function is also set. Forthe node identification information, a FQDN format, an IP address or thelike may be used. The higher-level apparatus is an EM, an NM or thelike.

Further, the SON Solution Information may be defined in an informationelement called “Served Cell Information” defined in the X2 SETUP REQUESTmessage and the X2 SETUP RESPONSE message instead of being defined inthe X2 SETUP REQUEST message and the X2 SETUP RESPONSE message. FIG. 5shows a setting example of the Served Cell Information in which SONSolution Information is added in its information element.

Further, the SON Solution Information may be defined in an ENBCONFIGURATION UPDATE message instead of being defined in the X2 SETUPREQUEST message and the X2 SETUP RESPONSE message. FIG. 6 shows an ENBCONFIGURATION UPDATE message in which SON Solution Information is addedin its information elements.

Referring to FIG. 1 again, the control unit 1101 sets a parameter(s)relating to the SON function in the eNB 100. Further, in the case wherethe eNB 100 is implemented by using a Distributed SON, the SON functionsuch as an ANR and a PCI Assignment is performed in the control unit1101. That is, in the control unit 1101, an ANR algorithm, a PCIAssignment algorithm or the like is performed and an optimalparameter(s) for network design is autonomously set.

The database unit 1103 stores information about the SON of an eNB(s)adjacent to the eNB 100. For example, the database unit 1103 storesinformation on whether a neighboring eNB is using a Distributed SON or aCentralised SON. Further, the database unit 1103 stores informationabout the SON function(s) supported by a neighboring eNB(s) and so on.

Note that the function of each component of the eNB 100 may beimplemented by using hardware, or may be implemented by using softwarethat is accomplished by causing a CPU or the like to execute a program.

Further, each of the EM and the NM also has an apparatus configurationsimilar to that shown in FIG. 1. For example, the signaltransmission/reception unit 1102 in the EM transmits a control messageto an eNB through a Type-1 interface. Further, in the case of anEM-Centralised SON or a Hybrid SON in which the SON function is disposedin the EM, the SON function such as an ANR and a PCI Assignment isperformed in the control unit 1101 in the EM.

Similarly, the signal transmission/reception unit 1102 in the NMtransmits a control message to the EM through a Type-2 interface.Further, in the case of an NM-Centralised SON or a Hybrid SON in whichthe SON function is disposed in the NM, the SON function such as an ANRand a PCI Assignment is performed in the control unit 1101 in the NM.

Next, a notification sequence of an SON function implementation methodby using SETUP REQUEST and X2 SETUP RESPONSE messages is explained withreference to FIG. 7.

Firstly, the control unit 1101 of the eNB 100 sets SON SolutionInformation in the eNB 100 (S11). In the case where the eNB 100 is usinga Centralised SON solution, the SON Solution Information may be set bythe EM or the NM. Next, the signal transmission/reception unit 1102 ofthe eNB 100 transmits the SON Solution Information in the eNB 100 toanother eNB (eNB 101) by using an X2 SETUP REQUEST message (S12).

The eNB 101, which has received the X2 SETUP REQUEST message, stores theSON Solution Information of the eNB 100 in the database unit (S13).Further, the eNB 101 sets the SON Solution Information of the eNB 101 inthe control unit (S14).

Next, the eNB 101 transmits the SON Solution Information in the eNB 101to the eNB 100 by using an X2 SETUP RESPONSE message (S15). Uponreceiving the X2 SETUP RESPONSE message, the eNB 100 stores the SONSolution Information of the eNB 101 in the database unit 1103.

Next, a notification sequence of an SON function implementation methodby using an ENB CONFIGURATION UPDATE message is explained with referenceto FIG. 8. The ENB CONFIGURATION UPDATE message is sent when a change ismade to the SON function implementation method in the eNB. For example,it is sent, when a Centralised SON is performed, when the EM thatmanages the eNB is changed, or when a new SON function is to besupported.

Firstly, the control unit 1101 of the eNB 100 updates SON SolutionInformation in the eNB 100 (S21). Next, the signaltransmission/reception unit 1102 of the eNB 100 transmits the updatedSON Solution Information of the eNB 100 to the eNB 101 by using an ENBCONFIGURATION UPDATE message (S22).

The eNB 101 overwrites the existing information with the updated SONSolution Information of the eNB 100 and thereby stores it in thedatabase unit (S23). Alternatively, the eNB 101 replaces the existinginformation with the updated SON Solution Information and thereby storesthe updated SON Solution Information in the database unit. Next, the eNB101 sends back an ENB CONFIGURATION UPDATE ACKNOWLEDGE message to theeNB 100 as a response message to the ENB CONFIGURATION UPDATE message(S24). By receiving the CONFIGURATION UPDATE ACKNOWLEDGE message, theeNB 100 can recognize that the update information of the SON SolutionInformation of the eNB 100 has been properly reflected in the eNB 101.

Next, a configuration example of the database unit 1103 included in theeNB 100 is explained with reference to FIG. 9. FIG. 9 shows whether ornot eNBs 101 to 106 adjacent to the eNB 100 support PCI optimization andMRO as SON functions. Further, FIG. 9 shows which of a Centralised SON,a Hybrid SON, and a Distributed SON is used in order to implement thePCI optimization and MRO. Further, FIG. 9 shows the node identifiers ofnodes that perform an SON for the cases where a Centralised SON or aHybrid SON is used.

For example, the eNB 101 supports the PCI optimization. The PCIoptimization in the eNB 101 is performed by using a Distributed SON. Inthis way, since the node that performs the PCI optimization is the eNB101 itself, “N/A”, which indicates that no external node performing theSON exists, is set in the PCI optimization node identifier. Further, theeNB 101 supports the MRO. The MRO in the eNB 101 is performed by using aHybrid SON, and the node performing the MRO is an EM 201.

Further, the eNB 102 supports the PCI optimization, but does not supportthe MRO. The PCI optimization is performed by using a Centralised SON,and the node performing the PCI optimization is an EM 200.

As described above, the database unit 1103 of the eNB 100 stores the SONfunction support status and the SON solution information for theneighboring eNB(s).

Next, an operation for sending information about an SON function betweeneNBs is explained. For example, the eNB 100 recognizes whether or not aneighboring eNB(s) has a PCI assignment optimization function based onwhether or not an SON Solution type for a PCI Assignment parameter isset in the SON Solution Information. If the neighboring eNB holds a PCIassignment optimization function, the eNB 100 needs to notify theneighboring eNB about a PCI change by using an ENB CONFIGURATION UPDATEmessage when the PCI of the eNB 100 is changed. On the other hand, ifthe neighboring eNB does not hold a PCI assignment optimizationfunction, the eNB 100 does not need to notify the neighboring eNB abouta PCI change by using an ENB CONFIGURATION UPDATE message when the PCIof the eNB 100 is changed.

Further, the eNB 100 can recognize the presence/absence of MRO functionsupport in the neighboring eNB based on whether or not an SON Solutiontype for MRO Algorithm parameter is set in the SON Solution Information.The eNB 100 needs neither to send information about a Handover Reportprocedure nor to start up a Mobility State Change procedure for aneNB(s) that does not support the MRO. In the example in FIG. 9, sinceeNBs 102 and 105 do not support the MRO function, the eNB 100 does notsend information about the Handover Report procedure and the MobilityState Change procedure necessary for the MRO operation to the eNBs 102and 105. As a result, it is possible to reduce the number of theX2AP-messages.

Similarly, the eNB 100 can recognize the presence/absence of ANRfunction support in the neighboring eNB based on whether or not an SONSolution type for ANR Algorithm parameter is set in the SON SolutionInformation, recognize the presence/absence of MLB function support inthe neighboring eNB based on whether or not an SON Solution type for MLBAlgorithm parameter is set in the SON Solution Information, recognizethe presence/absence of CCO function support in the neighboring eNBbased on whether or not an SON Solution type for CCO Algorithm parameteris set in the SON Solution Information, recognize the presence/absenceof Energy Saving function support in the neighboring eNB based onwhether or not an SON Solution type for an Energy Saving Algorithmparameter is set in the SON Solution Information, recognize thepresence/absence of ICIC function support in the neighboring eNB basedon whether or not an SON Solution type for ICIC Algorithm parameter isset in the SON Solution Information, and recognize the presence/absenceof CoC function support in the neighboring eNB based on whether or notan SON Solution type for CoC Algorithm parameter is set in the SONSolution Information.

By sending information about the presence/absence of SON functionsupport to each other among neighboring eNBs in advance as describedabove, it is possible to prevent change information for an SON functionthat is not supported in the neighboring eNB(s) and the like from beingtransmitted. As a result, it is possible to reduce the number of uselesscontrol messages and the like.

Further, as shown in FIGS. 4A and 4B, when an SON Solution typeparameter exists and the SON solution is a Centralised SON or a HybridSON, the node identifier information of the node that is implementingthat SON function can be set in the SON Solution Information. In FIGS.4A and 4B, an IP-address or a host name (FQDN format) is set as the nodeidentifier information. However, the node identifier information is notlimited to the IP-address and the host name (FQDN format). That is, anyidentifiers or any numbering system can be used, provided that they areuniquely identified in the network.

For example, in the example in FIG. 20, by the Identification of Nodeexecuting PCI Assignment algorithm of the SON Solution Information, whenan X2-link is established with a neighboring eNB, the eNBs 100, 102,104, 112, 110 and 108 can send information that the PCI assignmentoptimization functions of the eNBs 100, 102, 104, 112, 110 and 108 areimplemented by the EM 200 by using an X2 SETUP message. Therefore, whenthe PCI value of the cell of the eNB 100 is changed from 3 to 200, theeNB 100 sends an X2AP-message to the eNBs 106, 101, 103 and 105. Sincethe eNB 110 recognizes the fact that the PCI assignment optimizationfunction is implemented by the EM 200, the eNB 106 does not send theX2AP-message to the eNB 110.

Similarly, the eNB 105 can determine not to notify the eNB 112 about thesignal, and the eNB 101 can determine not to notify the eNBs 108 and 102about the signal. Therefore, eventually, the eNB 101 does not notify theeNBs 102 and 208 about the X2AP signaling in which the PCI assignmentoptimization is implemented by the same EM 200 as that for the eNB 100.That is, the eNB 101 needs to notify only the eNBs 106, 107 and 109about the X2AP signaling. Therefore, it is possible to reduce the numberof X2AP-messages transmitted between eNBs.

Similarly, Identification of Node executing ANR algorithm is nodeidentifier information of the node that is implementing an ANR function.Identification of Node executing MRO algorithm is node identifierinformation of the node that is implementing an MRO function.Identification of Node executing MLB algorithm is node identifierinformation of the node that is implementing an MLB function.Identification of Node executing CCO algorithm is node identifierinformation of the node that is implementing a CCO function.Identification of Node executing Energy Saving algorithm is nodeidentifier information of the node that is implementing an Energy Savingfunction. Identification of Node executing ICIC algorithm is nodeidentifier information of the node that is implementing an ICICfunction. Further, Identification of Node executing CoC algorithm isnode identifier information of the node that is implementing a CoCfunction.

By sending node identification information of the EM or the like that isimplementing a respective SON function between eNBs in this manner, itis possible to reduce the number of X2AP-messages as described above.

Next, an X2AP-message transmitting process flow in an eNB according tothe first exemplary embodiment of the present invention is explainedwith reference to FIG. 10. Firstly, the eNB 100 performs measurementcontrol necessary for an SON algorithm, detects a trigger forX2AP-message transmission for the purpose of sending a parameter(s)determined in the SON algorithm, and so on (S31). For example, when theeNB 100 has changed the PCI value in the eNB 100 itself, the eNB 100detects a trigger for X2AP-message transmission.

Next, the control unit 1101 of the eNB 100 acquires information aboutwhat kind of SON function is supported by a neighboring eNB(s) from thedatabase unit 1403 (S32). For example, when the neighboring eNB does notsupport any SON function relating to the PCI optimization, the controlunit 1101 determines not to transmit the X2AP-message relating to thePCI value change to the neighboring eNB. When the neighboring eNBsupports the SON function relating to the PCI optimization, the controlunit 1101 determines whether or not the node that is implementing theSON function is the same as its own node (S33). That is, when the nodethat is implementing the SON function in the eNB 100 is the EM 200, thecontrol unit 1101 determines whether or not the node that isimplementing the SON function in the neighboring eNB is the EM 200. Whenthe node that is implementing the SON function in the neighboring eNB isthe same as its own node, the signal transmission/reception unit 1102does not transmit the X2AP-message to the neighboring eNB. When the nodethat is implementing the SON function in the neighboring eNB isdifferent from its own node, the signal transmission/reception unit 1102transmits the X2AP-message to the neighboring eNB (S34).

An operation in the eNB 101 adjacent to the eNB 100 is explainedhereinafter. When the eNB 101 is notified that the PCI value has beenchanged in the eNB 100, the eNB 101 performs the processes in the stepsS31 to S33. When it is determined that the node implementing the SONfunction in the neighboring eNB is different from its own node in thestep S33, the eNB 101 may further determine whether or not the nodeimplementing the SON function in the neighboring eNB is the same as thatfor the eNB 100. When the node implementing the SON function in theneighboring eNB is the same as that for the eNB 100, the eNB 101 may nottransmit the X2AP-message to the neighboring eNB. Further, when the nodeimplementing the SON function in the neighboring eNB is different fromthat for the eNB 100, the eNB 101 may transmit the X2AP-message to theneighboring eNB.

As explained above, by using the communication system according to thefirst exemplary embodiment of the present invention, advantageouseffects explained below can be achieved.

As a first advantageous effect, since an eNB(s) sends information aboutthe support status of an SON function when an X2 link is established, aneNB(s) can recognize the support status of the SON function in theneighboring eNB. Therefore, the eNB(s) can prevent an X2AP-message frombeing transmitted to the eNB(s) that does not support the SON function.As a result, the eNB(s) can reduce the number of X2AP-messagetransmissions.

As a second advantageous effect, since an eNB(s) sends information aboutthe identifier of a node that is implementing an SON function when an X2link is established, an eNB(s) can recognize what kind of SON solutionis used to implement the SON of a neighboring eNB(s) and which node isimplementing the SON function. Therefore, the eNB(s) can determine theneed for transmitting an X2AP-message by comparing the node identifiers.As a result, it is possible to reduce the number of X2AP-messagetransmissions.

Further, in the case where a Relay node (RN) and a Donor eNB (DeNB)exist as shown in 3GPP TS36.300, the communication method according tothe first exemplary embodiment of the present invention can be appliedeven to an X2-interface between an RN and a DeNB and between an RN andanother RN. As a result, it is possible to reduce the number ofX2AP-signalings between the RN and the DeNB and between the RN and theRN.

Further, the first exemplary embodiment has been explained by using eNBsin accordance with the LTE. However, the invention according to thefirst exemplary embodiment can also be applied to 3G systems inaccordance with the W-CDMA. Further, the invention according to thefirst exemplary embodiment can also be applied to other wireless accesssystems in accordance with GERAN, Wimax, WLAN and so on. For example, inthe case where an RNC has an SON function as shown in 3GPP TS25.401, itis possible to reduce the number of the signalings necessary for the SONsuch as an RNSAP signal between RNCs by sending information about thesupport status of an SON function, the node identifier of a nodeimplementing an SON function, or the solution type of an SON function inan Iur-interface between RNCs.

Further, it is conceivable to perform an SON function such as MRO andICIC even between femto-base stations (HeNBs, HNBs), eNBs, or RNCs. Thatis, it is possible to send information such as the support status of anSON function, an SON solution type, and the node identifier of a nodeimplementing an SON function to each other between an HeNB and an HeNB,between an HeNB and an eNB, between an HeNB and an RNC, between an HeNBand an HNB, between an HNB and an HNB, between an HNB and an eNB,between an HNB and an RNC, and so on. As a result, it is possible toreduce the number of unnecessary signalings related to the SON betweenfemto-base stations or between a femto-base station and a macro-basestation.

Second Exemplary Embodiment

In the first exemplary embodiment, a method for sending informationabout a supported SON function, an SON solution and so on by using anX2AP-message between eNBs is explained. However, it is conceivable thatno X2-link is established between eNBs because of topographic reasonssuch as the presence of a mountain range between eNBs, or for thereduction of CAPEX/OPEX by the reduction of the X2-link band. In suchcases, if there is an interface between NMs, between EMs, or between anNM and an EM in an OAM system, information about how an SON function isimplemented may be sent by using that interface.

FIG. 11 is a table showing information about the SON function of an eNBto be sent from an NM to an EM through a Type-2 interface between the NMand the EM. The information shown in FIG. 11 corresponds to, forexample, a case where the SON Solution Information defined in FIG. 4 isadded in an EUtranRelation defined in GPP TS32.762 in whichspecifications relating to wireless access networks are specified. Inthis way, the EM or the eNB can recognize the SON function supportstatus in a neighboring eNB(s), as well as the SON solution type and thenode identifier of the node implementing the SON function. Theidentifier may be a DN (Distinguished name), an IP-address, an FQDN, orother forms of identifiers. That is, the identifier may be anyinformation that makes it possible to uniquely identify nodes within thenetwork.

As a result, similarly to the first exemplary embodiment, it is possibleto omit the transmission of an S1AP message for the purpose of the SONthrough a CN (Core Network) to an eNB(s) that does not support the SONfunction and/or to an eNB(s) for which the SON implementing node is thesame. Note that the method for adding SON Solution Information is notlimited to the configuration shown in FIG. 4. That is, any configurationcapable of sending information about the SON support status in aneighboring eNB(s), a solution type, and the node identifier of a nodeimplementing an SON can be used.

Further, the SON function notification method and the like can also beapplied to connection between systems having different wirelessaccesses, i.e., to an Inter-RAT (Radio Access Technology) scenario. AnSON function such as an ANR function and an MRO function can also beapplied to connection between different RATs, e.g., to connectionbetween an E-UTRAN using an LTE wireless access technique and a UTRANusing a W-CDMA wireless access technique. For example, by using an ANRfunction, an eNB in accordance with the LTE can automatically configureneighboring cell information in the network. In such a case, as shown inFIG. 12, it is also possible to directly connect an eNB 200 with an RNC201 between a UTRAN system and an E-UTRAN system and to send neighboringcell information to each other. The E-UTRAN system includes an eNB 200and an MME/S-GW 202. The UTRAN system includes an RNC 201, an MSC 203,and a NodeB 205 An SGSN 204 is used as a gateway apparatus that connectsthe UTRAN with the E-UTRAN. The present invention can be applied even tothis case. That is, information on an SON function support status, anSON solution type, and the identifier information of an SON implementingnode can be reciprocally sent between the eNB 200 and the RNC 201. As aresult, it is possible to reduce the number of unnecessary signalingsrelated to the SON between RATs.

Further, it is also possible to reciprocally send information on an SONfunction support status, an SON solution type, and the node identifierof an SON implementing node through a core network (MME, MSC, SGSN andso on) between an eNB and an RNC according to an S1AP protocol or anRANAP protocol. As a result, it is possible to reduce the number ofunnecessary signalings related to the SON between RATs.

Third Exemplary Embodiment

A purpose of the first and second exemplary embodiments according to thepresent invention is to reduce the number of unnecessary X2AP-messagesby sending information on an SON function implementing node, an SONfunction support status, and so on. In a third exemplary embodimentaccording to the present invention, an eNB does not directly sendinformation on the SON function implementing node, the SON functionsupport status, and so on, but instead specifies an X2AP-message(s) forwhich the reception is undesired among X2AP-messages transmitted from aneighboring eNB and sends its information in advance when an X2AP withthe neighboring eNB is established.

An X2AP establishing process flow is explained with reference to FIG.13. Firstly, a transmission source eNB determines an X2AP-message(s) forwhich the reception from the neighboring eNB is undesired (S31). Next,the transmission source eNB transmits the determined information byusing an X2 SETUP REQUEST message (S32). FIG. 15 shows an example of anX2 SETUP message. In FIG. 15, it is possible to set a ProhibitedX2AP-procedure parameter group, which is the information about anX2AP-message(s) for which the reception is undesired, in the X2 SETUPREQUEST message. For example, by setting as “Load Indication”, thetransmission source eNB indicates that the eNB does not want to receivea Load Indication procedure.

An eNB, which has received the X2 SETUP REQUEST message, memorizes theinformation of the X2AP-message that the transmission source eNB doesnot want to receive (S33). Further, it performs control so that theneighboring eNB that has transmitted this eNB does not start thespecified X2AP-procedure. Next, the eNB, which has received the X2 SETUPREQUEST message, determines an X2AP-message(s) for which the receptionis undesired (S34) and sends the X2AP-message(s) of which the receptionis undesired by using an X2AP SETUP RESPONSE (S36).

Further, when a change is made to the Prohibited X2AP-procedureparameter group, as shown in FIG. 14, firstly, the information of theX2AP-message for which the reception is undesired is updated in the eNB100. The eNB 100 sets the changed Prohibited X2AP-procedure parametergroup, which is the information of the X2AP-message for which thereception is undesired, by using ENB CONFIGURATION UPDATE, and sends itsinformation to the neighboring eNB (S42).

Next, the eNB 101 updates the X2AP-procedure that the eNB 100 does notwant to receive (S43). As a result, the eNB can recognize theX2AP-message that the neighboring eNB does not want to receive inadvance, thus achieving an advantageous effect of reducing unnecessarythe number of X2AP-messages. Needless to say, the ProhibitedX2AP-procedure parameter, which is the information of the X2AP-messagefor which the reception is undesired, may be added in other messages orother parameters. Further, the Prohibited X2AP-procedure is not limitedto the configuration shown in FIG. 15, provided that it can sendinformation on what kind of X2AP-procedure is undesired to be received.Next, the eNB 101 transmits ENB CONFIGURATION UPDATE ACKNOWLEDGE to theeNB 100 as a response signal to the ENB CONFIGURATION UPDATE (S44).

As explained above, by using the communication system according to thethird exemplary embodiment of the present invention, it is possible tonotify a neighboring eNB(s) about information about an X2AP-message(s)of which the transmission is unnecessary when an X2-link is established.As a result, it is possible to prevent unnecessary X2AP-messages frombeing transmitted, thus making it possible to reduce the number of theX2AP-message transmissions.

Note that the present invention is not limited to the above-describedexemplary embodiments, and various modifications can be made withoutdeparting from the scope and spirit of the present invention.

For example, although the present invention is described as a hardwareconfiguration in the above-described exemplary embodiments, the presentinvention is not limited to the hardware configurations. The processesof an eNB(s) shown in FIGS. 7, 8, 10, 13 and 14 can be implemented bycausing a CPU (Central Processing Unit) to execute a computer program.In such a case, the computer program can be stored in various types ofnon-transitory computer readable media and thereby supplied tocomputers. The non-transitory computer readable media includes varioustypes of tangible storage media. Examples of the non-transitory computerreadable media include a magnetic recording medium (such as a flexibledisk, a magnetic tape, and a hard disk drive), a magneto-optic recordingmedium (such as a magneto-optic disk), a CD-ROM (Read Only Memory), aCD-R, and a CD-R/W, and a semiconductor memory (such as a mask ROM, aPROM (Programmable ROM), an EPROM (Erasable PROM), a flash ROM, and aRAM (Random Access Memory)). Further, the program can be supplied tocomputers by using various types of transitory computer readable media.Examples of the transitory computer readable media include an electricalsignal, an optical signal, and an electromagnetic wave. The transitorycomputer readable media can be used to supply programs to computerthrough a wire communication path such as an electrical wire and anoptical fiber, or wireless communication path.

Although the present invention is explained above with reference toexemplary embodiments, the present invention is not limited to theabove-described exemplary embodiments. Various modifications that can beunderstood by those skilled in the art can be made to the configurationand details of the present invention within the scope of the invention.

This application is based upon and claims the benefit of priority fromJapanese patent application No. 2011-251454, filed on Nov. 17, 2011, thedisclosure of which is incorporated herein in its entirety by reference.

REFERENCE SIGNS LIST

-   100, 101, 200 eNB-   201 RNC-   202 MME/S-GW-   203 MSC-   204 SGSN-   205 NodeB-   1101 CONTROL UNIT-   1102 SIGNAL TRANSMISSION/RECEPTION UNIT-   1103 DATABASE UNIT

The invention claimed is:
 1. A communication system, comprising: a firstcommunication apparatus; and a second communication apparatus thatperforms data transmission/reception with the first communicationapparatus, wherein the first communication apparatus comprises atransmission unit that transmits information to the second communicationapparatus, the information being used to determine whether or notautonomous setting information should be transmitted from the secondcommunication apparatus to the first communication apparatus, wherein,when the autonomous setting information of the first communicationapparatus is managed in a higher-level apparatus, the firstcommunication apparatus transmits node identifier information of thehigher-level apparatus to the second communication apparatus, andwherein, when the autonomous setting information is changed in the firstcommunication apparatus, the first communication apparatus transmits thechanged autonomous setting information to a communication apparatusincluding, among another communication apparatus adjacent to the firstcommunication apparatus, a communication apparatus of which theautonomous setting information is managed in a higher-level apparatusdifferent from the higher-level apparatus managing the autonomoussetting information of the first communication apparatus.
 2. Thecommunication system according to claim 1, wherein the first and secondcommunication apparatuses comprise base station apparatuses used in amobile communication system, and the autonomous setting information istransmitted by using a communication message defined between the basestation apparatuses.
 3. The communication system according to claim 1,wherein the autonomous setting information includes information about aplurality of SON (Self Organizing Networks) functions, and wherein thefirst communication apparatus notifies the second communicationapparatus about an SON function supported in the first communicationapparatus among the plurality of SON functions.
 4. The communicationsystem according to claim 3, wherein the second communication apparatustransmits information about an SON function that is supported in thefirst communication apparatus to the first communication apparatus anddoes not transmit information about an SON function that is notsupported in the first communication apparatus to the firstcommunication apparatus.
 5. The communication system according to claim1, wherein the autonomous setting information includes information abouta plurality of SON Self Organizing Networks) functions, and wherein thefirst communication apparatus transmits, among information about theplurality of SON functions, information about an SON function of whichtransmission from the second communication apparatus is undesired to thesecond communication apparatus.
 6. The communication system according toclaim 5, wherein the second communication apparatus does not transmitinformation about an SON function for which it is notified thattransmission from the first communication apparatus is undesired, to thefirst communication apparatus.
 7. The communication system according toclaim 1, wherein the plurality of SON functions includes at least one ofa PCI (Physical Cell ID) Assignment, an ANR (Automatic NeighborRelation), MRO (Mobility Robustness Optimization), MLB (Mobility LoadBalancing), CCO (Coverage and Capacity Optimization), Energy Saving,ICIC (Inter-cell Interference Coordination), and CoC (Cell outageCompensation).
 8. A base station apparatus adjacent to a first basestation apparatus, the base station apparatus comprising: a transmissionunit that transmits information to the first base station apparatus, theinformation being used in the first base station apparatus to determinewhether or not autonomous setting information should be transmitted tothe base station apparatus, wherein, when the autonomous settinginformation of the base station apparatus is managed in a higher-levelapparatus, the transmission unit transmits node identifier informationof the higher-level apparatus to the first base station apparatus, andwherein, when the autonomous setting information is changed in the basestation apparatus, the base station apparatus transmits the changedautonomous setting information to a communication apparatus including,among another communication apparatus adjacent to the base stationapparatus, a communication apparatus of which the autonomous settinginformation is managed in a higher-level apparatus different from thehigher-level apparatus managing the autonomous setting information ofthe base station apparatus.
 9. A data transmission method performed in abase station apparatus adjacent to a first base station apparatus, thedata transmission method comprising: transmitting information to thefirst base station apparatus, the information being used in the firstbase station apparatus to determine whether or not autonomous settinginformation should be transmitted to the base station apparatus; andwhen the autonomous setting information of the base station apparatus ismanaged in a higher-level apparatus, transmitting node identifierinformation of the higher-level apparatus to the first base stationapparatus, wherein, when the autonomous setting information is changedin the base station apparatus, the base station apparatus transmits thechanged autonomous setting information to a communication apparatusincluding, among another communication apparatus adjacent to the basestation apparatus, a communication apparatus of which the autonomoussetting information is managed in a higher-level apparatus differentfrom the higher-level apparatus managing the autonomous settinginformation of the base station apparatus.
 10. A non-transitory computerreadable media storing a program that causes a computer in a basestation apparatus adjacent to a first base station apparatus to execute:transmitting information to the first base station apparatus, theinformation being used in the first base station apparatus to determinewhether or not autonomous setting information should be transmitted tothe base station apparatus; and when the autonomous setting informationof the base station is managed in a higher-level apparatus, transmittingnode identifier information of the higher-level apparatus to the firstbase station, wherein, when the autonomous setting information ischanged in the base station apparatus, the base station apparatustransmits the changed autonomous setting information to a communicationapparatus including, among another communication apparatus adjacent tothe base station apparatus, a communication apparatus of which theautonomous setting information is managed in a higher-level apparatusdifferent from the higher-level apparatus managing the autonomoussetting information of the base station apparatus.
 11. The communicationsystem according to claim 1, wherein, when the autonomous settinginformation is changed in the first communication apparatus, the firstcommunication apparatus transmits the changed autonomous settinginformation to the communication apparatus including, among said anothercommunication apparatus adjacent to the first communication apparatus, acommunication apparatus of which the autonomous setting information isnot managed in any higher-level apparatus.
 12. The communication systemaccording to claim 1, further comprising a third communication apparatusthat receives the changed autonomous setting information from the firstcommunication apparatus.
 13. The communication system according to claim12, wherein the third communication apparatus transmits the changedautonomous setting information to a communication apparatus including,among another communication apparatus adjacent to the thirdcommunication apparatus, at least one of a communication apparatus ofwhich the autonomous setting information is managed in a higher-levelapparatus different from the higher-level apparatus managing theautonomous setting information of the first communication apparatus anda communication apparatus to which the autonomous setting information isnot transmitted from any higher-level apparatus.
 14. The communicationsystem according to claim 12, wherein the third communication apparatustransmits the changed autonomous setting information to a communicationapparatus including, among another communication apparatus adjacent tothe third communication apparatus, a communication apparatus of whichthe autonomous setting information is managed in a higher-levelapparatus different from the higher-level apparatus managing theautonomous setting information of the first communication apparatus anda communication apparatus to which the autonomous setting information isnot transmitted from any higher-level apparatus.
 15. The base stationapparatus according to claim 8, wherein, when the autonomous settinginformation is changed in the base station apparatus, the base stationapparatus transmits the changed autonomous setting information to thecommunication apparatus including, among said another communicationapparatus adjacent to the base station apparatus, a communicationapparatus of which the autonomous setting information is not managed inany higher-level apparatus.